The present invention relates to an apparatus for cooling high-temperature particles and more particularly an apparatus for air-cooling high-temperature clinker in a cement burning process or for cooling high-temperature particles in a process of burning or sintering steel, lime stone or alumina.
Japanese Patent Application Nos. 2226/1983 (laid open under No. 128243/1984) and 2227/1983 (laid open under No. 128244/1984) disclose a cooling apparatus which can overcome the problems encountered in conventional grate type coolers for air-cooling high-temperature cement clinker. The above-mentioned cooling apparatus will be described with reference to FIGS. 8 and 9. First referring to FIG. 8, reference numeral 31 designates a first cooling zone in which high-temperature particles such as cement clinker is air-quenched; 32, a second cooling zone which is disposed below the first cooling zone 31 to gradually cool the cement clinker which has been quenched in the first cooling zone 31; and 33, a rotary kiln for burning cement.
The first cooling zone 31 comprises a vertical guide tube 34 which is disposed at the inlet and is adapted to temporarily hold high-temperature cement clinker and to prevent the cement clinker from being rapidly spread in the radially outward direction; a conical or pyramidal body 35 which has a large number of air distributing holes, is disposed coaxially with the guide tube 34, spaced apart therefrom by a predetermined distance and has a very gentle inclination angle smaller than an angle of repose; a motion acceleration device 36 which is vertically movable between the top of the conical or pyramidal body 35 and the guide tube 34, thereby accelerating the movement of cement clinker along the outer surface of the body 35 in the radially outward direction; and an air-cooling device 37 which supports the vertical guide tube 34 and is adapted to cool the outer surface thereof.
The second cooling zone 32 comprises a packed moving bed type cooling device 38 in which rapidly cooled cement clinker is packed into layers which move downward.
Still referring to FIG. 8, reference numeral 39 designates a control rod for controlling the downward movement of cement clinker; 40, a scraper ring; 41, a discharge scraper; 42, a turntable; 43, a conveyor for discharging the cooled cement clinker out of the system; 44, a main air supply line for supplying the air for cooling the high-temperature (or first cooling) zone; 45, a blower; 46, an air supply line for supplying the air for cooling the low-temperature (or second cooling) zone; 47, a blower; 48, an air compressor; 49, a directional control valve; 50, an air supply line for supplying the air to activate the motion acceleration device; 51, an auxiliary air supply line for supplying the air to cool the high-temperature zone; 52, an air discharge line for discharging air from the motion acceleration device; 53, a valve; and 54, an air supply line for supplying the combustion air to a calcination furnace.
Next referring to FIG. 9, the relationship among the vertical guide tube 34, the conical or pyramidal body 35 and the motion acceleration device 36 and the construction of the motion acceleration device 36 will be described. The motion acceleration device 36 is in the form of a piston whose upper end terminates into a cone with a large number of holes and is mounted on a stationary member 55 disposed below the guide tube 34 in coaxial relationship with the axis 56 of the guide tube 34 for vertical movement. The motion acceleration device 36 comprises a hollow conical head 57 with a bottom, an outer tube 58 and an inner tube 59 which are formed integral with the head 57. A high pressure chamber 60 is defined between the outer and inner tubes 58 and 59. The stationary member 55 comprises an inner tube 61 and an outer tube 62. A lower end portion of the inner tube 59 is inserted into the inner tube 61 while a lower portion of the outer tube 58 is air-tightly fitted over the outer tube 62. The motion acceleration device 36 is vertically slidable relative to the stationary member 55. The stationary member 55 has an air inlet 63 communicated with the air supply line 50, an air inlet 64 communicated with the auxiliary air supply line 51 and an air outlet communicated with the air discharge line 52.
With the cooling apparatus of the type described above, cement clinker 67 which is burned in the rotary kiln 33 to a high temperature of about 1350.degree. C. is fed into the vertical guide tube 34 as indicated by a broken-line arrow 68, temporarily remains therein and then discharged over the conical or pyramidal body 35. Due to the slope of the conical or pyramidal body 35, the pressure of the air flowing upwards through the air distributing holes as indicated by the arrows 71 and the vertical movement of the motion acceleration device, cement clinker is distributed radially outwardly. Since cement clinker is forced to flow along the outer surface of the conical or pyramidal body 35 radially outwardly in the first cooling zone 31, it is rapidly and uniformly cooled to about 950.degree. C. by the air flowing upwardly as indicated by the arrows 71. Cement clinker thus rapidly cooled is then fed into the packed moving bed type cooling device 38 which constitutes the second cooling zone 32 and is gradually cooled by the air supplied through the cooling air supply line 46. Cement clinker thus cooled is discharged by the conveyor 43 out of the system.
The air from the main air supply lines 44 is at room temperature and flows in the directions indicated by the arrows 69, 70, 71 and 72 so that the air is heated to about 1050.degree. C. and is used as the combustion air in the rotary kiln 33. The air at room temperature from the cooling air supply line 46 passes through the packed moving bed type cooling device 38 and is heated to about 800.degree. C. and flows into the air supply line 54 for supplying the combustion air into the calcination furnace.
The compressed air from the air compressor 48 is switched by the directional control valve 49 to flow into the air supply line 50 for supplying the air for activating the motion acceleration device or into the auxiliary air supply line 51 for supplying the cooling air to the high temperature zone. More particularly, as best shown in FIG. 9, the compressed air supplied through the auxiliary cooling air supply line 51 flows through the air inlet 64, the inner tube 61 and the inner tube 59 into the hollow space in the conical head 57. The air is discharged upwardly from the conical head 57 into the vertical guide tube 34, thereby mixing and cooling cement clinker remaining therein. When the compressed air is forced to flow through the air supply line 50 for supplying the air to activate the motion acceleration device, the valve 53 is closed. Then the compressed air from the line 50 flows into the air inlet 63 and through the space defined between the inner and outer tubes 61 and 62 to the high pressure chamber 60 where the compressed air is blocked. As a result, the motion acceleration device 36 is forced to move upwardly relative to the stationary member 55. On the other hand, when the supply of the compressed air to the line 50 is interrupted while the valve 53 is opened, the compressed air in the high pressure chamber 60 is discharged through the air discharged line 52 so that the motion acceleration device 36 is caused to move downwardly by its own weight relative to the stationary member 55. Thus, when the valve 53 is closed to introduce the compressed air through the line 50 into the high pressure chamber 60 and when the supply of the compressed air to the line 50 is interrupted while the valve 53 is opened, thereby discharging the compressed air from the high pressure chamber 60, the motion acceleration device 36 is forced to vertically move relative to the stationary member 55. In this case, a slight vertical stroke is sufficient enough to accelerate the movement of cement clinker along the outer surface of the conical or pyramidal body 35 so that the motion acceleration device vertically reciprocates a stroke indicated by 57 and 57a. However, when a large lump of cement clinker is fed into the vertical guide tube 34, the motion acceleration device is caused to move down to the position indicated by 57b so that the large lump drops not through the conical or pyramidal body 35 but directly downwardly and is discharged out of the cooling apparatus through a discharge port (not shown) later at a suitable time.
With the apparatus for cooling high-temperature particles of the type described above, the stability of the moving layer of high-temperature particles along the outer surface of the conical or pyramidal body is adversely affected due to the fluctuations in flow rate and pressure of the mixing and cooling air flowing through the motion acceleration device, the disturbances in mixing action in the high-temperature particle layer, the changes in pressure distribution between the high-temperature particle layers both caused by the vertical movement of the motion acceleration device, the variation in particle size distribution of the high-temperature particles fed from the rotary kiln, the response of the change in pressure distribution between the layers caused by the drop impact pressure, and the other variables of high-temperature particles in the vertical guide tube. For instance, high-temperature particles are abnormally forced to flow from the vertical guide tube to the conical or pyramidal body. As a result, the whole burning process including a step in the cooling apparatus is adversely affected.
Furthermore with the cooling apparatus of the type described above, in order to remove large and medium lumps in high-temperature particles, the motion acceleration device is forced to move to the lower dead point. Then the large and medium lumps are caused to drop together with the high-temperature particles remaining in the vertical guide tube and are removed out of the cooling apparatus later at a suitable time.
However, when large and medium lumps frequently admix in the high-temperature particles, they cannot be removed because of the insufficient capacity of the lower storage zone and because of a time required for naturally cooling the large and medium lumps dropped together with the high-temperature particles, resulting in shutdown of the rotary kiln and the cooling apparatus.
The present invention was made to overcome the above and other problems encountered in the cooling apparatus of the type described above.
A primary object of the present invention is, therefore, to provide an apparatus for cooling high-temperature particles in which variable factors in the vertical guide tube will not adversely affect the stability of the moving layer of high-temperature particles along the surface of the conical or pyramidal body.
A further object of the present invention is to provide an apparatus for cooling high-temperature particles in which high-temperature large and medium lumps mixed in the high-temperature particles from the rotary kiln can be crushed while their temperatures are still high, whereby the performacne of the cooling apparatus can be improved and enhanced.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of some preferred embodiments thereof taken in conjunction with the accompanying drawings.